Translation:They are feeding chickens
The English sentence needs to be: "They are 1) feeding the chicken(s); 2) feeding a chicken; 3) feeding chickens." As far as the Swahili sentence, I guess it is fine. I just feel uncomfortable not having an object infix when the object is animate, so I probably would have said "Wanawalisha kuku", which I hope is not wrong, but maybe not required.
By the way, thank you for all your responses to my questions. Very much appreciated.